Syntheses of α-tocopheryl glycosides by glucosidases.

Enzymatic syntheses of water-soluble α-tocopheryl glycosides were carried out in di-isopropyl ether using amyloglucosidase from Rhizopus mold or β-glucosidase isolated from sweet almond. Optimum conditions for the amyloglucosidase were: α-tocopherol 0.5 mmol, d-glucose 0.5 mmol, 400 activity unit (AU) amyloglucosidase, 0.2 mM pH 7 phosphate buffer and 72 h; and for the β-glucosidase: α-tocopherol 0.5 mmol, d-glucose 0.5 mmol, 110 AU β-glucosidase, 0.1 mM pH 6 phosphate buffer and 72 h. Out of 11 carbohydrates employed, amyloglucosidase reacted only with d-glucose to give 50% of 6- O-(α-D-glucopyranosyl)α-tocopherol. However, the β-glucosidase gave 6- O-(β- d-glucopyranosyl)α-tocopherol, 6- O-(α- d-galactopyranosyl)α-tocopherol, 6- O-(β- d-galactopyranosyl)α-tocopherol, 6- O-(α- d-mannopyranosyl)α-tocopherol and 6- O-(β- d-mannopyranosyl)α-tocopherol in yields ranging from 10–25%. Water solubility of 6- O-(α- d-glucopyranosyl)α-tocopherol was 26 g/l at 25°C. α-Tocopheryl glycosides showed antioxidant activities with IC₅₀ values from 0.5 to 1 mM and angiotensin-converting enzyme (ACE) inhibitory activity with IC₅₀ values from 1.3 to 2.6 mM. [ABSTRACT FROM AUTHOR]